261 



inflection (Plate XXXVIII. d, d) is but slightly bent inward, with a thick and smooth 

 border ; the longitudinal extent of this inflected part is about 4^ inches, closely repeat- 

 ing, as far as it is preserved, the characters of the more perfectly preserved angle of the 

 type specimen (Cut, fig. 1, d, d)*. An oblique longitudinal wide and shallow channel 

 intervenes on the inner side of the ramus between the inflection (Plate XXXVIII. 

 fig. 1, d, d) and the low tuberous terminationf of the postalveolar ridge (ib. & fig. 2, t), 

 about an inch and a half behind the socket of the last molar (m 3). This channel is 

 continued backward with a partial interruption, caused by the forward extension of the 

 inflected angle or hind border of the ascending ramus (ib. fig. 2, a, e). This part is 

 broken away in the type specimen. 



In no part of the oblique channel (ib. b) occupying and mainly forming the inner 

 surface of the ascending ramus of the jaw is there any trace of inlet of a dentary canal ; 

 in this respect, as in the somewhat unusual position of that inlet or entry, the present 

 mandible agrees with the type fragment J. Some nerve or vessel has left its impress 

 along the middle of the channel, but has quitted it for contiguous soft parts without 

 penetrating the bone. 



The outer surface of the ascending ramus rises from th'e line of the anterior inflection 

 (d) with a feeble vertical concavity, speedily changed to a convexity curving outward to 

 the thick obtuse lower boundary (Plate XXXVI. & Plate XXXVIII. fig. 1, h) of the 

 ectocrotaphyte depression (ib. f). The fore part of this depression is formed by the cor- 

 responding part of the rising ramus (ib. and fig. 2, q), which commences opposite the 

 hind part of the last molar (m 3), and at a distance outside it of 1 inch 3 lines. The 

 base of the " coronoid " plate (Plate XXXVIII. fig. 2, q, h) describes a curve, concave 

 outward, of which base an extent of 5 inches (in a straight line) is preserved. The 

 process is broken off in both rami ; it was thickest at the fore part of its base (Plate 

 XXXVIII. fig. 4, q), which here gives half an inch. The dental nerves and vessels 

 groove the inner and back part of the base of the coronoid before penetrating it obliquely 

 in the same position (at 0, figs. 1 & 2) as that in the type specimen (Cut, fig. 1, 0). 



Between the postinternal alveolar process (Plate XXXVIII. figs. 1, 2, t) and the base of 

 the coronoid process, is an irregular shallow channel (ib. u), narrowing as it passes back- 

 ward to the dental canal (0). The depth of the mandibular ramus at the back of the 

 last tooth-socket is 4 inches, the thickness of the ramus at the fore part of the origin of 

 the coronoid process is 2 inches G lines. 



The interspace between the right and left last socket is 3 inches 6 lines. The breadth 

 of the mandible, taken anterior to the origin of the coronoid process, is 7 inches 8 lines ; 

 whence the jaw gradually expands to the condyles. We may estimate its breadth at the 

 outsides of these, from the cavities (Plate XXXVII. fig. 3, g, 27) receiving them, to have 

 been 1 foot, or thereabouts. 



The outer surface of the horizontal ramus (Plate XXXVI. fig. 1, 32, q) is smooth, very 

 convex vertically where it advances from the ascending ramus, but rising with a slight 



* Op. cit. pi. 4. figs. 3 & 5, a. t Loc. cit. figs. 2 & 3, b. % Loc. cit. fig. 3. 



